Sewing machine

ABSTRACT

A zigzag stitch sewing machine has the lateral displacement of the needle actuated by a cam selected from a stack of cams mounted in fixed and/or removable manner on a common shaft to which they are secured for rotation with the shaft. The shaft is rotated by the principal drive shaft of the machine ensuring the to-and-fro movement of a needle bar into a pivoting cradle, the cam ensuring the pivoting of the cradle by means of a transmission element. The transmission element comprises a lever hinged to the frame and provided with a feeler in contact with the profile of said cam, a rod driven in a sliding movement, hinged to the cradle, and an intermediate element displaceable between a support surface presented by said lever and a ramp axially rigid with said rod. The intermediate element is loosely mounted on the rod around which it is movable over a circular arc. The ramp is the profile of a cam mounted on said rod.

United States Patent Fresard et al.

1451 v Oct.2,1973

SEWING MACHINE Inventors: Marcel Fresard; Francis Plomb;

' Ollndo Baruffa. all of Geneva. Switzerland Assignee: Melina S.A., Tribourg, Switzerland Filed: Apr. 6, 1972 Appl. No.: 241,694

1 Foreign Application Priority Data Apr. 20, 197] Switzerland 5713/7] U.S. Cl. 112/158 B Int. Cl D05b' 3/00 Field of Search ll 2/l58 R, 158 A, s 112/1588 References Cited UNITED STATES PATENTS 2/l96l Koike ll2/l58 A l2/l962 Shimada", 112 158 A FOREIGN PATENTS OR APPLICATIONS Francem' 112 158 A Primary Examiner-Werner H. Schroeder Attorney-Emory L, Groff et al,

[57] ABSTRACT A zigzag stitch sewing machine has the lateral displacement of the needle actuated by a cam selected from a stack of cams mounted in fixed and/or removable manner on a common shaft to which they are secured for rotation with the shaft. The shaft is rotated by the principal drive shaft of the machine ensuring the to-and-fro movement of a needle bar into a pivoting cradle, the 2 cam ensuring the pivoting of the cradle by means of a transmission elemenLThe transmission element comprises a lever hinged to the frame and provided with a feeler'in contact with the profile of said 'cam, a rod driven in a sliding movement,hinged to the cradle, and

an intermediate element displaceable between a support surface presented by said lever and a ramp axially rigid with said rod. The intermediate element is loosely mounted on the rod around which it is movable'over a circular arc. The ramp is the profile of a cam mounted on said rod.

15 Claims, 8 Drawing Figures PATENTEDUBT 2 13 I 3,762,349

' sum 2 or e PATENTEDUBT 2 3.762.349

SHEET 8 [IF 6 *1 I MMYA'AYYM E 5% il 0 v om SEWING MACHINE The invention relates to a zigzag stitch sewing machine and more particularly to a control device for the lateral displacements of the needle and the movements of the feed-dog of such a machine.

Numerous types of sewing machines enabling simultaneous sewing with running stitch and with a zigzag stitch, including buttonhole stitching, are already known. The lateral displacements of the needle in such machines are generally actuated by cams driven either manually, or automatically by the principal drive shaft of the machine.

It is an object of the present invention to provide a machine which comprises a combination of automatic control cams and of manual control cams enabling the adjustment at the same time of the amplitude of the lateral displacements of the needle and of its decentering if necessary, as well as the length of the stitches, depending on the movements of the feed-dog and the feed direction.

In this machine, the lateral displacements of the needle are controlled by a cam selected from a stack of cams mounted in fixed and/or removable manner on a common shaft with which they are rotatable'.These cams can therefore be an integral part of the machine or interchangeable or partially interchangeable. The common shaft of said cams is rotated, in known manner, by the principal drive shaft of the machine ensuring the to-and-fro movement of the needle bar in a pivoting cradle. The cam ensures the pivoting of the cradle through a transmission element.

In the machine according to the invention, the transmission element comprises a lever hinged to the frame and provided with a feeler in contact with the profile of said cam, a rod driven in a sliding movement, hinged to the cradle, and an intermediate element capable of being moved between a support surface presented by said lever and a ramp axially rigid with said rod.

In order that the invention may be more fully understood, one embodiment of a sewing machine according to the invention is described below, purely by way of illustrative but non-limiting example, with reference to the accompanying diagrammatic drawing, in which:

FIG. 1 is a view in elevation of said embodiment;

FIG. 2 is a partial view, in horizontal section, along the line II-ll of FIG. 1, on a larger scale;

FIG. 3 is a partial view in cross-section along the line III-III of FIG. 2;

FIG. 4 is a view in partial longitudinal section along the line IV-IV of FIG. 2;

FIG. 5 is an enlarged view of the profile of the manual adjustment cam for the length of the stitch;

FIG. 6 is an enlarged view of the profile of the cam for compensating manufacturing tolerances of the automatic control cams of the feed-dog;

FIG. 7 is an enlarged view of the profile of the two paths of the manual adjustment cam .for the width of the stitch and of the decentering of the sewing and of the cam path causing reversal of the direction of advance of the feed-dog on sewing a buttonhole; and

FIG. 8 is a diagrammatic view showing the position of the intermediate element of the control mechanism for the lateral displacements of the needle on the adjustments shown in FIG. '7. a

The frame of the machine shown comprises abase' l, a free arm 2 containing the feed-dog drive mechanism,

a column 3 in which an electric motor is housed and an upper arm 4 in which a principal drive shaft 5 coupled to said motor is housed. The upper arm 4 bears at its free end a head 6 in which a cradle is mounted into which a needle bar 7 is driven in a substantially vertical to-and-fro movement, by the principal drive shaft 5. The cradle is itself mounted pivotally around an axis parallel to the needle bar 7, its pivoting around said axis being controlled by a mechanism housed inside the upper arm 4.

This sewing machine is of the type described in the Swiss patent No. 297.807, and the oscillation of the cradle which causes the lateral movements of the needle for the zigzag stitch sewing is actuated by a cam selected from a stack of cams 8 mounted on a common shaft and rotatable therewith. These cams can therefore be an integral part of the machine, or interchangeable, or partially interchangeable. This stack of cams 8 is rotated in synchronous manner with the principal drive shaft 5 of the machine to which said common shaft is coupled.

The transmission element transmitting the oscillating movement to the cradle, not shown, is actuated by'the cam selected from the stack of cams 8. The transmission element comprises a lever'9 provided with a feeler 10 in contact with the cam profile and mounted on an axle 11 carried by the frame (see FIG. 2). An intermediate element 12, mounted on lever arms 13 oscillating around a rod 14 hinged to the cradle, is supported by one of its ends provided with a follower 15 against a support surface 16 of the lever 9, and by its other end provided with a follower 17 against the profile of the cam 18 rigid with said rod 14.

It will be understood that in operation, the rod 14 is driven by a longitudinal to-and-fro movement whose amplitude is a function of the position of the follower 15 of the intermediate element 12 on the support surface 16 of the lever 9 with respect to the pivoting axle 11 of the latter, and of the profile of the cam selected in the stack of cams 8. This longitudinal movement of the rod 14 is effected against the action of a return spring, not shown. It determines the amplitude of the oscillations-of the cradle and consequently that of the lateral displacements of the needle. The centering of the needle is determined by the cam 18 which can be rotated with the rod 14 by a mechanism controlled by the cam profile 20 of a cam 21 actuated by a control knob 52. This mechanism is identical with the mechanism for positioning the follower 15 on the support surface 16 of the lever 9 controlled by the cam profile 22 of this same cam 21 (see FIG. 3).

This mechanism comprises a lever pivoting around an axle 24 against the action of a return spring 25, of which lever oneof the arms .23 bears a follower 26 supported against the cam profile 22 of the cam 21. Another arm 27 of this lever is articulated to the arm 28 of the lever bearing the intermediate element 12 whose displacements along the support surface 16 of the lever 9 are thus controlled by the cam profile 22 of the cam 21. The relative angular position of the lever arms .23 and '27 is adjustable and fixed by means of a screw 19.

It is understood that an arm 27( of a lever articulated to an eccentric pin 29 of the cam 18 enables actuation in an identical manner of rotation of the cam 18 from the cam profile 20 by means of afollower 30 which :is carried by another arm 23 of this lever which also pivots around the axle 24 against the action of a spring 25.. The relative angular position of the lever arms 23' and 27 is also adjustable and fixed by means of the screw 19'.

The stack of cams 8 comprises also control cams for the movement of the feed-dog housed in the end of the free arm 2 of the machine opposite the needle. This feed member for the parts to be sewn is kept in motion from the principal shaft of the machine, the amplitude and direction of movement being controlled, in known manner, through a substantially vertical rod 31 (see FIG. 4). In fact, as described in the abovementioned Swiss patent No. 297.807, for each angular position which this rod 31 can occupy, there corresponds a forward or backward movement of said feeddog. Only the mechanism intended to give its various angular positions to the rod 31 is shown in the drawing.

The rod 31, which is axially fixed, has at its upper end and arm 32 whose free end is connected by a link 33 to one of the arms 34 of a lever 35 of which one other arm 37 is provided with a feeler 38 in contact with the profile of the selected control cam. The lever 35 is pivoted on an eccentric hub 39 mounted on an axle 36. The hub 39 has a radial finger 40 provided with a feeler 41 in contact with the profile 'of the cam 42 mounted on a control axle 43 and capable of being driven manually by a knob 44 in order to compensate manufacturing tolerances of the profile of the control cam of the lever 35 with which the feeler 38 comes into contact.

The selection of the cams from the stack of carns 8 intended to control respectively the lateral displacements of the needle and the movements of the feed-dog in the course of a given sewing operation is effected by means of the control knob 45 of a rocker 46 by means of a rack drive. The control axle of the knob 45 bears for this purpose a toothed drive pinion 47, for a toothed sector 48 rigid with the axle of the rocker 46 and a positioning disc 49 having, on one hand, positioning slots 53 for the arms 50 and 51 of the rocker 46 and, on the other hand, ball-positioning holes 54, each corresponding to the positioning of one of said slots 53 facing a pin 55 for the locking of the rocker 46 in the selected position.

A manual control lever 56 for the separation of the feelers 10, 38 from the stack of cams 8 for the purpose of selecting cams and simultaneous unlocking of the positioning disc 49 is mounted at the end of an axle 57 bearing an arm 58 which, when it is moved in clockwise direction, with reference to FIG. 4, causes the pivoting, through a connecting rod 59, of a lever 60, pivoted at 36 above the lever 35, in anti-clockwise direction, with reference to FIG. 2. This lever 60 has an elongated slot 61 in which is engaged a pin 62 provided by the end of the arm of the lever 34 and to which the link rod 33 is articulated. It will be understood that on its pivoting in anticlockwise direction, with reference to FIG. 4, the lever 60 drives the lever arm 34 through its pin 62 engaged in its slot 61. By so doing, it separates the feeler 38 from the stack of cams 8.

The lever 60 has also a slot 63 with two branches in which is engaged a pin 64 which bears the free end of one of the arms 65 of a lever of which the other arm 66 is supported, through its free end against a pin 67 of the lever 9. The locking pin 55 of the rocker 46 is, on the other hand, fixed to the arm of the lever 65 at its middle portion. It will be understood that on its pivoting in anticlockwise direction, with reference to FIG. 2, the lever 60 causes a displacement of the pin 64 of the lever 65 towards the end of the branch 68 of its slot 63, the separation of the feeler 38 from the stack of cams 8 by driving the arm 34 of the lever 35 by its pin 62, the separation by the lever arm 65, of the pin 55 from its position of locking the positioning disc 49 of the rocker 46 and the separation of the feeler 10 from the stack of cams 8 by the lever arm 66 acting on the pin 67 of the lever 9.

The feelers l0 and 38 are mounted in a manner displaceable in height parallel to the axis of the stack of cams 8 and facing the latter, on the lever 9, and the lever arm 37 respectively. One of the feelers 10 is connected simultaneously to the end of the arm 50 of the rocker 46, while the other 38 is rigid with to a plate 69 occuring opposite the end of the arm 51 of the rocker 46 intended to raise it. A support stop limits the vertical displacement of the plate 69 along the stack of cams 8 from above to below. When the arm 51 of the rocker is lowered beyond this support stop of the plate 69 by acting on knob 45, it is no longer followed by the plate 69, while the arm 50 continues to displace the feeler l0 upwardly along the stack of cams 8. Under these conditions, the selection of cams from the stack of cams 8 controlling the lateral displacements of the needle continues without simultaneously changing the automatic control of the feed.

The manual control lever 56 for the separation of the feelers 10, 38 is restored to its resting position shown in FIG. 4 by a return spring 70. If it is desired to displace the rod 31 temporarily from its position where it controls the forward operation of the feed-dog into its position where it controls the backward operation of the feed-dog, it suffices to actuate the lever 56 in anticlockwise direction. It then rotates the arm 58 in anticlockwise direction with reference to FIG. 4, and this arm 58 causes the lever 60 to pivot by means 'of the link rod 59 in clockwise direction with reference to FIG. 2. The lever 60 then drives the connecting rod 33 through the pin 62, projecting into its slot 61, to which it is pivoted. By so doing, it actuates the arm 32 of the rod 31 against the effect of a return spring 83 and brings said rod 31 temporarily into its position where it controls the rearward operation of the feed-dog.

A lever 74 pivoted at 75 and having at its ends feelers 76, 77 respectively in contact with a cam profile 78 of the cam 21 and a cam profile 79 of a cam 71 also enables the reversal of the direction of movement of the feed-dog in the production of buttonholes. In fact, on its pivoting in anti-clockwise direction, with reference to FIG. 2, the end of the lever 74 in the vicinity of the feeler 77 causes the rod 31 to pivot, through the pin 73 which its arm 32 bears, into its position where it controls forward operation of the feed-dog with an amplitude equal to that selected in rearward operation. This pivoting of the lever 74 is controlled by the cam profile 78 of the cam 21 when the cam profile 79 of the cam 71 occurs in buttonhole sewing position, in rearward operation (F, FIG. 5).

The two arms of the lever 74 respectively bearing the feelers 76 and 77 are articulated to one another at 75 against the action of a return spring (see FIG. 4) supported against a pin 86 rigidly fixed to one of the two arms and displaceable in a slot 87 of the other arm (see FIG. 2). It is thus possibleto freely manipulate the knob 52 and to pass the top of the cam profile 78 under the feeler 76 whatever the position of the feeler 77 on the cam profile 79.

When the feeler of the lever 9 is in contact with the profile of a suitable cam for the formation of a buttonhole, selected from the stack of cams 8 and the zone F (see FIG. 5) of the cam profile 79 of the cam 71 facing the feeler 77 of the lever 74, all of the successive operations of sewing the left lip of the buttonhole in forward operation and decentering to the left (A), of

the upper bolt in centered forward operation (B), of the right lip of the buttonhole in forward operation and decentering to the right (C), of the lower bolt in centered rearward operation (D) and with decentering to the right of the stop of the buttonhole (E), (see FIGS. 7 and 8) are controlled by means of the knob 52 for actuating the cam 21 of which the respective cam profiles 78, 22 and are represented in expanded view in FIG. 7.

The cam profiles remaining between I and G correspond to sewing with increase in the width of the stitch centered between l and H from a nul value to a maximum, then with diminution of the width of the stitch and decentering to the right between H and G to a nul value (see FIG. 8).

The cam 71 mounted on the same axle 43 as the cam 42 has also a cam profile 72 into contact with which comes a feeler 80 on an actuating lever 81 engaged freely around the rod 31 for controlling the movements of the feed-dog. This device enables manual control, by actuating the knob 44, .of the movements of the feeddog when the latter are not controlled by a cam from stack of cams 8. This manual control device is similar to that which has been described in the U.S. Pat. No. 3.149.592.

The arm 81 rotates the rod 31 around its axis as a function of the movements of the feeler 80 along the cam profile 72 by means of a radial pin 82 fast to the rod 31 in contact with which it is held by one of the ends of a spring 83, of which the other end is supported against another radial pin 84 fast to the rod 31.

The evolution of the cam profile 72, shown in FIG. 5, is as follows:

In the zone K, the cam 72 controls the length of the stitch in rearward operation from a nul amplitude to a predetermined amplitude -l v). This amplitude continues to increase, but more rapidly in the zone L up to a maximum amplitude 4 before reaching the automatic control zone P of the feed-dog, in which the profile of the cam 42 (FIG. 6) intervenes to compensate the manufacturing tolerances of the automatic control cam of the stack of cams 8 used and applying the feeler 38 against the selected cam.

In leaving the point 0 in reverse direction, the cam 72 controls in the zone N the stitch length in forward operation from a nul amplitude to a predetermined amplitude +1 and this amplitude continues to increase, but more rapidly, in the zone M to a maximum value +4 I The regulating mechanism of the machine described above hence enables:

a. selection of a cam from a stack of cams 8 for simple sewing or buttonhole sewing, or two cams for automatic control of zigzag sewing, by actuating the cam selection knob 45 after having unlocked it by simultaneous actuation of the lever 56 in clockwise direction;

b. simultaneous control of the stitch width, its centering and the feed direction of the fabric to be sewn by subsequent actuation of the control knob 52;

c. manual control and in temporary manner of the 'feed of the fabric to be sewn in'rearward operation by actuation of the lever 56 in anti-clockwise direction;

d. engagement of the automatic control of the feed of the fabric to be sewn and compensation of the manufacturing tolerances of the profile of the automatic control cams for the feed of the fabric to be sewn by actuation of the control knob 44;

e. regulation of the length of the stitch and the direction of feed of the fabric outside of the automatic control of the feed-dog by actuation of the control knob Numerous modifications of the embodiment of the control mechanism described above could be envisaged. Thus, the cams 18, 21, 71 could have different profiles. Similarly, the arrangement of the various levers of the mechanism could be different, especially in sewing machines of a different type. The cam profiles 42 and 71 could also be united on a same cam, for example. All such modifications should be regarded as within the scope of the invention as defined by the appended claims.

We claim:

1. In a zigzag stitch sewing machine including a frame, a freearm, an upper arm, a column connecting said arms at one of their respective ends, a head at the free end of said upper arm, a principal drive shaft in said upper arm, an oscillating cradle in said head, a needle bar mounted in said cradle and a feed-dog housed in the free end of said free arm, a stack of cams mounted on a common shaft to which they are rigidly secured, lateral displacements of said needle bar being actuated by a cam selected from said stack of cams, said common shaft being rotated by said principal drive shaft ensuring the to-and-fro movement of said needle bar in said oscillating cradle, a transmission element acting on said selected cam and ensuring the oscillation of said cradle, said transmission element comprising a lever hinged to said frame, a feeler on said lever and in contact with the profile of said selected cam, a support surface on said lever, a rod hinged to said cradle, a ramp axially rigid with said rod, an intermediate element displaceable between said support surface on said lever and said ramp, said rod driven in a sliding movement by displacement of said intermediate element.

2. A machine according to claim 1, wherein said intermediate element is loosely mounted on said rod around which it is movable in a circular are.

3. A machine according to claim 1, wherein said ramp is the profile of a cam mounted on said rod.

4. A machine according to claim 3, wherein said cam is rigid with said rod.

5. A machine according to claim 3, including a double profile cam the first profile of which actuates the displacement of said intermediate element along said support surface of said lever, and the second profile of which actuates the rotation of said cam mounted on the rod hinged to the cradle, thereby enabling adjustment of the width of the stitch by means of said first camprofile and the centering of the sewing operation by means of the second cam profile.

6. A machine according to claim 1, wherein said stack of cams comprises cams for actuating the movements of said feed-dog, the mechanical connection between said selected cam and said feed-dog comprising a lever of which one of the arms is provided with a feeler in contact with the profile of said selected cam and the other arm of which rotates around its axis a substantially vertical control rod for control of the amplitude and direction of movement of the feed-dog.

7. A machine according to claim 6, wherein said other lever arm rotates said control rod for the amplitude and the direction of movement of the feed-dog by means of a link hinged to an arm rigid with said rod.

8. A machine according to claim 6, including a member for selecting two cams from said stack of cams and simultaneously bringing into contact with said earns the feeler of said lever producing displacement of the cradle and the feeler of the lever rotating said control rod for the amplitude and feed direction of said feed-dog.

9. A machine according to claim 8, wherein said selection member is a rocker controlled by a manual actuating member, said rocker including two arms one of which lifts one of said feelers opposite said stack of cams while the other is lowered with the other feeler and conversely.

10. A machine according to claim 8, including a control member for a mechanism ensuring the simulta neous unlocking of the selection member for the cam and separation of the feelers in contact with said stack of cams.

11. A machine according to claimlO, wherein said control member of the mechanism for unlocking the selection member and separation of saidfeelers of the stack of cams also controls a mechanism for instantaneous changing of the direction of feed of the feed-dog.

12. A machine according to claim 1, including a manual control member for a first cam for manual adjustment of the amplitude and direction of feed of the feeddog and, when said first cam is in an inactive position, said control member providing manual adjustment of a second cam enabling compensation manufacturing tolerances of the control cams for the amplitude and direction of feed of the feed-dog forming part of said stack of earns.

13. A machine according to claim 5, wherein the cam profiles of said double profile cam are formed so as to enable simultaneous manual adjustment of the stitch width and of the centering of the sewing when actuated by a selected cam in said stack of earns.

14. A machine according to claim 13, wherein said double profile cam for the simultaneous manual adjustment of the stitch width and of the centering of the sewing includes also a third cam profile controlling a mechanism cooperating with a second cam profile of said cam for the simultaneous manual adjustment of the stitch length and of the feed direction of the feed-dog, said mechanism enabling the reversal of the feed direction of the feed-dog to be produced, in the fabrication of buttonholes.

15. A machine according to claim 14, wherein said mechanism for reversing the feed direction of the feeddog in the fabrication of buttonholes comprises a lever of which one of the arms isprovided with a feeler in contact with said third cam profile of said double profile cam and the other arm is provided with a feeler cooperating with said second cam profile of said cam for adjusting the feed, said other arm cooperating with a member for rotating said control rod for the feed direction of the feed-dog. 

1. In a zigzag stitch sewing machine including a frame, a free arm, an upper arm, a column connecting said aRms at one of their respective ends, a head at the free end of said upper arm, a principal drive shaft in said upper arm, an oscillating cradle in said head, a needle bar mounted in said cradle and a feed-dog housed in the free end of said free arm, a stack of cams mounted on a common shaft to which they are rigidly secured, lateral displacements of said needle bar being actuated by a cam selected from said stack of cams, said common shaft being rotated by said principal drive shaft ensuring the to-and-fro movement of said needle bar in said oscillating cradle, a transmission element acting on said selected cam and ensuring the oscillation of said cradle, said transmission element comprising a lever hinged to said frame, a feeler on said lever and in contact with the profile of said selected cam, a support surface on said lever, a rod hinged to said cradle, a ramp axially rigid with said rod, an intermediate element displaceable between said support surface on said lever and said ramp, said rod driven in a sliding movement by displacement of said intermediate element.
 2. A machine according to claim 1, wherein said intermediate element is loosely mounted on said rod around which it is movable in a circular arc.
 3. A machine according to claim 1, wherein said ramp is the profile of a cam mounted on said rod.
 4. A machine according to claim 3, wherein said cam is rigid with said rod.
 5. A machine according to claim 3, including a double profile cam the first profile of which actuates the displacement of said intermediate element along said support surface of said lever, and the second profile of which actuates the rotation of said cam mounted on the rod hinged to the cradle, thereby enabling adjustment of the width of the stitch by means of said first cam profile and the centering of the sewing operation by means of the second cam profile.
 6. A machine according to claim 1, wherein said stack of cams comprises cams for actuating the movements of said feed-dog, the mechanical connection between said selected cam and said feed-dog comprising a lever of which one of the arms is provided with a feeler in contact with the profile of said selected cam and the other arm of which rotates around its axis a substantially vertical control rod for control of the amplitude and direction of movement of the feed-dog.
 7. A machine according to claim 6, wherein said other lever arm rotates said control rod for the amplitude and the direction of movement of the feed-dog by means of a link hinged to an arm rigid with said rod.
 8. A machine according to claim 6, including a member for selecting two cams from said stack of cams and simultaneously bringing into contact with said cams the feeler of said lever producing displacement of the cradle and the feeler of the lever rotating said control rod for the amplitude and feed direction of said feed-dog.
 9. A machine according to claim 8, wherein said selection member is a rocker controlled by a manual actuating member, said rocker including two arms one of which lifts one of said feelers opposite said stack of cams while the other is lowered with the other feeler and conversely.
 10. A machine according to claim 8, including a control member for a mechanism ensuring the simultaneous unlocking of the selection member for the cam and separation of the feelers in contact with said stack of cams.
 11. A machine according to claim 10, wherein said control member of the mechanism for unlocking the selection member and separation of said feelers of the stack of cams also controls a mechanism for instantaneous changing of the direction of feed of the feed-dog.
 12. A machine according to claim 1, including a manual control member for a first cam for manual adjustment of the amplitude and direction of feed of the feed-dog and, when said first cam is in an inactive position, said control member providing manual adjustment of a second cam enabling compensation manufacturing tolerances of the control cams for the amplitude and direction of feed of the feed-dog forming part of said stack of cams.
 13. A machine according to claim 5, wherein the cam profiles of said double profile cam are formed so as to enable simultaneous manual adjustment of the stitch width and of the centering of the sewing when actuated by a selected cam in said stack of cams.
 14. A machine according to claim 13, wherein said double profile cam for the simultaneous manual adjustment of the stitch width and of the centering of the sewing includes also a third cam profile controlling a mechanism cooperating with a second cam profile of said cam for the simultaneous manual adjustment of the stitch length and of the feed direction of the feed-dog, said mechanism enabling the reversal of the feed direction of the feed-dog to be produced, in the fabrication of buttonholes.
 15. A machine according to claim 14, wherein said mechanism for reversing the feed direction of the feed-dog in the fabrication of buttonholes comprises a lever of which one of the arms is provided with a feeler in contact with said third cam profile of said double profile cam and the other arm is provided with a feeler cooperating with said second cam profile of said cam for adjusting the feed, said other arm cooperating with a member for rotating said control rod for the feed direction of the feed-dog. 